1. Field of the Invention
This invention generally relates to apparatus control systems and, in particular, to such systems which include mechanical cam switching means and associated electronic control circuitry.
2. Statement of the Prior Art
Various types of automated control systems for multifunction apparatuses are well known and widely used. In the area of apparatuses referred to as household appliances, the most common form of automated control system generally includes a mechanical cam which controls various switches for connecting power to the multiple operational functions involved. The cams are produced to allow their respective operational function to be operative during a certain amount of cam rotation and the speed of cam rotation is controlled to determine the operational time of the function. Rotational power for the cam can be derived from either mechanical sources, such as springs, or electromechanical sources, such as motors or solenoids. Likewise, the speed of cam rotation can be controlled either mechanically or electrically. Examples of such automatic control systems using electrically driven cams and electrical circuitry to control the rate of rotation of the cam are disclosed by U.S. Pat. Nos. 3,350,606, 3,360,902 and U.S. Pat. No. Re. 29,086. When used in simple control applications, such mechanisms are reliable and relatively inexpensive. However, difficulties are encountered when adapting such mechanisms to more complicated control environments because the mechanical complexity of the control apparatus greatly increases. Under these circumstances, the cost of producing the mechanism greatly increases.
Another major area of multifunction apparatus control system development has been that of digital or solid state electronics. Generally, through the use of relatively low cost digital circuits, such as the CMOS type, it is relatively easy to construct a control system with a high degree of complexity in the control function. More expense is generally incurred in the interface area between the digital electronics and the operational functions which generally require high power energy sources.